Three years ago, many dozens of Republicans and Democrats arranged to sit side by side at the State of the Union. The break with decades of tradition was orchestrated in hopes of persuading the country that civil discourse and bipartisan collegiality had gained renewed value in Congress after the assassination attempt on Rep. Gabrielle Giffords.

The roster of cross-aisle seating arrangements remained plenty big the next year, but there was a noticeable falloff in 2013. And, unless the situation changes in the last hours before President Barack Obama arrives at the Capitol on Tuesday, spotting crossover seatmates in the House chamber looks to be a genuinely difficult task this year.

The putative tradition, like the annual House "civility retreats" more than a decade ago, looks to be fading toward oblivion. The soft ending nonetheless underscores how the bilious nature of today’s congressional culture can slowly poison even the most benignly symbolic and fleetingly telegenic gestures toward cultivating common ground.

A survey of two dozen senators, all of whom connected with senators of the other party in 2012, found only four couples volunteering plans for keeping the custom alive on Tuesday night.

Colorado Democrat Mark Udall will sit with an Energy and Natural Resources Committee colleague, Alaska Republican Lisa Murkowski, which makes sense since they are the two who wrote to the bipartisan House and Senate leadership two weeks ago to urge them to make bipartisan seating a permanent custom at the president’s annual speech. West Virginia Democrat Joe Manchin III and Illinois Republican Mark S. Kirk, who share one of the few noticeably warm personal bipartisan friendships in Congress, will hang out together.

So will Nevada Republican Dean Heller and Rhode Island Democrat Jack Reed, who are leading the stalled push to extend long-term jobless benefits, and Maine’s Senate delegation, moderate Republican Susan Collins and Democrat-affiliated independent Angus King. (Seventeen other states have senators in both camps, and all but nine of the 43 multidistrict states have at least one House member from each party.)

There was no better luck from spot checks with 12 House members who had also participated in the past. The most prominent pairing: Republican Matt Salmon and his Arizona colleague Ron Barber, the Democrat who’s clinging to the Tucson seat previously held by Giffords, his former boss.

(Remember that Giffords’ fragile recovery compelled her to resign a year after being shot in the head, and her subsequent prominence as an advocate for tighter background checks and size limits on ammunition clips has not advanced the cause of federal gun control a single notch.)

Barber and Salmon sat together last year and were the two House signatories on the letter to the leadership. The missive has received no public response from the leaders, which in hindsight is not a surprise. Shuffling the seating diagram was not their idea; it was the brainchild of the centrist think tank Third Way, and Udall pushed it the hardest from the outset.

Back in 2011, the leaders were openly wary, at least initially, about the idea of creating an exception to the strict and decades-old segregation of the parties on either side of the House’s center aisle — Republicans on the west side, oddly to the president’s left, and Democrats on the east. (The custom has its roots in the British Parliament’s seating plan.)

So radical was the proposal that Senate Majority Leader Harry Reid and Senate Minority Leader Mitch McConnell actually took a formal meeting on it before agreeing to acquiesce on senatorial seat-shifting without formally endorsing the idea. Speaker John A. Boehner announced that nothing in the rules prevents lawmakers from sitting wherever they want in the hall of the House — which some took as a sign his troops should feel free to find a new perspective on the proceedings for one night, but others viewed as a subtle signal that rank-and-file Republicans need not feel pressure to wander in any way across the aisle.

The four leadership teams have strayed little from the custom of sitting together in groups. But Boehner, of course, is already spoken for in the bipartisan dating game; as speaker, the Ohio Republican is obligated to sit on the rostrum, in one of those high-backed chairs designed by Jefferson, and make nationally televised small talk and eye contact with Vice President Joseph R. Biden Jr. all night long.

For better or worse, creating a widespread game of musical chairs would deny the television audience one of the State of the Union’s most recognized visuals: the robotic way that lawmakers from the president’s party stand and applaud, while members from the other party reflexively sit on their hands, whenever he says something the slightest bit provocative.

That ritual is catnip for late-night comics and really annoying to independent voters. But midterm elections are all about bucking up the base, so liberal Democrats and conservative Republicans can’t be given blunt reminders too often about which side is which.

Members didn't like the cutesy nickname that quickly took hold of this little gesture of goodwill — "date night" — but the symbolism creates just another moment to remember how much life in Congress is like life in high school.

After all, Udall said of bipartisanship the other day: “If we can’t demonstrate it through the simplest of acts — talking with one another, sitting next to one another at a very important speech — if we can’t do that, then really the public should give up on us.”